The present invention relates to a damper valve for a hydraulic power-assisted steering system, and more particularly, to a damper valve located between a control valve and a power steering motor in a hydraulic power-assisted steering system.
It is known to locate a damper valve between a control valve and a power steering motor in a hydraulic power-assisted steering system. Generally, a damper valve is associated with each hydraulic conduit that connects the control valve to the power steering motor.
U.S. Pat. No. 6,003,427 discloses a damper valve for use in a hydraulic power-assisted steering system. The damper valve includes axial bores that are covered by spring plates. Recesses allow fluid access to each axial bore and as fluid pressure within the respective axial bores increases, the spring plate opposite the recess flexes to allow fluid flow through the damper valve. The damper valve also includes a bolt with an axial duct. The axial duct acts as a fluid bypass allowing fluid flow through the damper valve without passing through an axial bore. An adjustable screw partially extends into the axial duct of the bolt to restrict the flow of the fluid bypass. The adjustable screw allows the bypass flow through the axial duct to be calibrated.
The present invention is a damper valve located between a control valve and a power steering motor in a hydraulic power-assisted steering system. The damper valve comprises a housing having axially opposite first and second end portions and an intermediate portion interposed between the first and second end portions. The first end portion is for fluid communication with the control valve and the second end portion is for fluid communication with the power steering motor. A flow restricting element is located within the housing and is movable through portions of the housing including the intermediate portion by fluid flow through the housing. The damper valve further includes a biasing element for restraining movement of the flow restricting element toward the first end portion of the housing. An orifice is formed between the flow restricting element and the housing for restricting fluid flow greater than a predetermined amount through the housing from the second end portion toward the first end portion.